Arctic Ocean may be releasing its methane

New source of greenhouse gas identified, but not yet explained

A group of researchers has expressed concern that the Arctic may contribute more methane to the atmosphere than previously estimated.

While working out the past history of climate change is relatively straightforward (especially for the past fifty to one hundred years, for which we have direct measurements), predicting its future is more difficult – and one of the uncertainties is the role of the potent, but less-common greenhouse gas, methane.

Methane stored in both permafrost (which is melting) and methane hydrates (methane trapped in marine reservoirs) are vulnerable to being released into the atmosphere as the planet warms.

However, neither of these are the source of methane observed in new research published in Nature Geosceince by the Jet Propulsion Laboratory’s Erik Kort.

Working with the HIPPO (HAIPER Pole-to-Pole Observations) research team, Kort and his collaborators found patches of methane in remote Arctic regions while seeking to map atmospheric greenhouse gas concentrations on a global basis.

As reported in New Scientist, in methane-rich regions “about 2 milligrams of the gas” is released per square meter of ocean, each day. Kort told New Scientist that a possible source of the methane is marine bacteria surviving in low-nutrient environments.

Should a warming environment cause that methane to be released into the atmosphere, it would need to be included in predictive models.

This makes new research to be published by the National Oceanographic and Atmospheric Administration in an upcoming issue of Geophysical Research Letters worth watching out for.

Summarised by Science magazine’s “Science Shots” here, the research shows that the heat stored in Earth’s oceans has continued to rise, even while recent weather has damped atmospheric warming.

The research is a compilation of temperature measurements from the upper 2000 meters of the ocean – and it’s worth noting that over the time span covered by the NOAA study, the error in measurement grows consistently smaller. ®